Organo phosphorus herbicides

ABSTRACT

O-alkyl-O-(3-methyl-6-nitrophenyl)-N-secondary butyl-phosphorothionoamidate, which possesses herbicidal properties.

This application is a divisional of application Ser. No. 474,444, filedMay 29, 1974, now U.S. Pat. No. 3,936,433 which in turn is acontinuation-in-part of the copending application Ser. No. 182,523 filedSeptember 21, 1971, now abandoned.

The present invention relates to the new phosphothionoamidate, to theherbicidal composition and to the use as a herbicide.

More particularly, the present invention pertains to the compound of theformula, ##EQU1## to the herbicidal composition containing as an activeingredient the compound of the formula (I) and to the use of thecompound of the formula, ##EQU2## wherein R is methyl or ethyl, as aherbicide.

The present compounds are useful for controlling weeds both in uplandand paddy fields, such as grass family weeds, for example barnyardgrass, large crab grass, water foxtail, etc. and broad-leaved weeds, forexample redroot pigweed, common lambsquarter, monochoria, slenderspikerush, etc.

The compounds of this invention may be synthetized by reacting athionophosphoric chloride of the formula, ##EQU3## WHEREIN R is asmentioned above with 3-methyl-6-nitrophenol, in an organic solvent inthe presence of an acid binding agent.

Examples of the solvent used in this invention include aromatic solventssuch as benzene and toluene, and ketones such as acetone and methylisobutyl ketone, and acetonitrile, etc.

Examples of the acid binding agents include inorganic bases such aspotassium carbonate and sodium hydroxide, tertiary amines such aspyridine and triethylamine, and a mixture thereof.

The reaction temperature varies depending on the kind of the solvent oracid binding agent to be used. The reaction is preferably carried out ata temperature of from room temperature to about 120°C. for 2 to severalhours.

Examples of the compounds synthetized by the above method are asfollows. ##EQU4##

Compounds having similar structure to that of the compounds of thisinvention are found in U.S. Pat. No. 2,552,576. However, they aredifferent from the compounds of this invention in that they have onlynitro group or groups as the substituents for the phenyl group and thattheir use is directed to insecticides and fungicides.

Also, U.S.S.R. Pat. No. 183,743 and Czechoslovak Pat. No. 127,221describe the present compounds. However, these compounds are describedto have only limited use in insecticides, fungicides and miticides andnot to have found the excellent herbicidal activity thereof.

Further, Dutch Pat. Nos. 6,916,095 and 6,916,096, U.S. Pat. No.2,074,790, and Belgian Pat. No. 745,633 describe herbicidal action ofcompounds having structure resembling that of the compounds of thisinvention.

Furthermore, U.S. Pat. No. 3,472,920 and 3,636,143 also describeherbicidal action of the compounds having structure resembling that ofthe present compounds. However, they are different in structure from thecompounds of this invention.

The present invention have firstly found the excellent herbicidalactivity of the compounds of this invention for which 3-methyl, 6-nitrogroups on the benzene ring and sec-butyl attached to nitrogen atom areessential.

The herbicidal characteristics of the compounds of the present inventionare described in the following:

When subjected to pre-emergence treatment of weeds in paddy field, thecompounds display strong herbicidal activities against a wide scope ofweeds such as, for example, barnyard grass (Echinochloa crus-galli),slender spikerush (Eleocharis acicularis), monochoria (Monochoriaviaginalis Presl.), false pimpernel (Linderna pyxidaria), toothcup(Rotala indica Koehne), etc. More surprisingly, the compounds cansuccessfully control the aforesaid weeds without any phytotoxicity totransplanted rice seedings. Therefore, the present compounds are quiteexcellent as herbicides for paddy rice fields. Further, when applied toupland fields, the present compounds have strong herbicidal activitieson many weeds, e.g. grass family weeds such as barnyard grass(Echinochloa crus-galli), large crabgrass (Digitaria sanguinalid), greenfoxtail (Setaria viridis) and water foxtail (Alopecurus aequalis), andsuch broad-leaved weeds as common purslane (Portulaca oleracea), redrootpigweed (Amaranthus retroflexus), common lambsquarter (Chenopodiumalbum) and chickweed (Stellaria media), and can effectively control theaforesaid weeds without any phytotoxicity to crops such as, for example,rice, radish, soy bean, pea, carrot and cotton. Therefore, the compoundsmay be applied to cereals, beans and vegetables, orchards, turfs,pasture lands and non-crop lands.

The present compounds are extremely low in toxicity to mammals andfishes.

In actual application, the compounds of the present invention may beused as they are or may be used in the form of any of such preparationsas granules, dusts, wettable powders emulsifiable concentrates, oilspray and aerosol. These preparations are desirably used so as to be inconform to the kinds and sizes of crops and to the purposes ofapplication. In formulating the present compounds, there are used suchsolid carriers as, for example, talc, bentonite, clay, kaolin,diatomaceous earth, vermiculite and calcium hydroxide; and such liquidcarriers as, for example, benzene, alcohols, acetone, xylene, dioxane,methyl naphthalene and cyclohexanone. In actual application, the presentcompounds may be enhanced and ensured in effectiveness by urging them inadmixture with surface active agents such as spreaders and stickers andthe like. It is also possible to use the present compounds in admixturewith fungicides, insecticides, nematocides, other herbicides and thelike agricultural chemicals and with fertilizers.

The present invention is illustrated in further detail below withreference to examples. All parts and percentages are by weight.

EXAMPLE 1

25 parts of the compound (2), 5 parts of a surface active agent of thepolyoxethylene acetylallylester type and 70 parts of talc werethoroughly pulverized and mixed together to obtain a wettable powder.

EXAMPLE 2

30 parts of the compound (2), 20 parts of an emulsifier of thepolyethylene glycol ether type and 50 parts of cyclohexanone werethoroughly mixed together to obtain an emulsifiable concentrate.

EXAMPLE 3

8 parts of the compound (2), 38 parts of bentonite, 50 parts of clay and4 parts of sodium lignosulfonate were thoroughly pulverized and mixedtogether. The resulting mixture was sufficiently kneaded with water, andthen granulated and dried to obtain granules.

In order to substantiate the prominent effects of the present compoundsas herbicides, detailed illustration is given below with reference totypical test examples, in which the names of the compounds arerepresented by the numbers of the previously exemplified compounds.

TEST EXAMPLE 1

Pre-emergence application:

Seeds of barnyard grass, large crabgrass, radish, common purslane,redroot pigweed and false pimpernel were individually sowed in flowerpots. After covering the seeds with soil, test compounds in such amountsas shown in Table 1 were individually applied to the soil. Thereafter,the test plants were growth in a greenhouse and after 20 days from theapplication, the herbicidal effects of the individual compounds wereinvestigated to obtain the results as set forth in Table 1. Herbicidaleffects were evaluated by the numerals ranging from 0 (not damaged) to 5(completely killed). All the compounds were formulated into emulsifiableconcentrates, and aqueous dilutions thereof were used.

                                      Table 1                                     __________________________________________________________________________    Herbicidal effects by pre-emergence application.                              __________________________________________________________________________                          Amount of                                                                     active                                                                              Herbicidal effects on                             Name of               ingredient                                                                          Barnyard                                                                            Large      Common                                                                              Redroot                                                                             False                compound              (g./are)                                                                            grass crabgrass                                                                           Radish                                                                             purslane                                                                            pigweed                                                                             pimpernel            __________________________________________________________________________    (1)                   50    5     5     0    5     5     5                                          25    5     5     0    5     5     5                                          12.5  4     5     0    5     4     4                                          6     4     4     0    4     4     3                    (2)                   50    5     5     0    5     5     5                                          25    5     5     0    5     5     5                                          12.5  5     5     0    5     5     5                                          6     5     5     0    4     4     5                    (iso)C.sub.3 H.sub.7 NHS                                                                            50    5     4     1    2     2     2                    ∠P∠       25    3     2     0    0     1     0                    CH.sub.3 OO           12.5  1     0     0    0     0     0                                          6     0     0     0    0     0     0                    U.S. Pat. No. 3,074,790                                                       (iso)C.sub.3 H.sub.7 NHS                                                                            50    5     5     2    5     4     4                    ∠P∠       25    3     4     0    4     3     3                    CH.sub.3 OO           12.5  2     2     0    2     0     1                                          6     0     1     0    0     0     0                    Belgian Pat. 690,911                                                          U.S. Pat. No. 3,472,920                                                       n-C.sub.3 H.sub.7 --NHS                                                       ∠P∠       50    1     2     0    1     1     1                    CH.sub.3 OO           25    0     0     0    0     0     0                                          12.5  0     0     0    0     0     0                    U.S.R. Pat. 183,743                                                           (CH.sub.3).sub.2 NO                                                           ∠P∠       50    0     0     0    0     0     0                    (CH.sub.3).sub.2 NO   25    0     0     0    0     0     0                                          12.5  0     0     0    0     0     0                    Czech. Pat. 127,221                                                           __________________________________________________________________________

Test Example 2

Wagner pots of 14 cm. in diameter, which had been packed individuallywith 1.5 kg. of paddy field soil, were brought into the state of paddyfields. To the pots were transplanted rice seedings at the 3-leavesstage. Further, seeds of barnyard grass were sowed in the pots and,after covering with soil, the test plants were grown in a greenhouse. Onthe second day after the sowing given amounts of test compounds wereindividually applied to the soil under water lodged condition.Broadleaved weeds germinated were monochoria, false pimpernel andtoothcup. After 25 days the herbicidal effects and the phytotoxicitythereof to the rice seedings were investigated to obtain the results asset forth in Table 2. The herbicidal effects and the phytotoxicity wereevaluated by numerals ranging from 0 (not damaged) to 5 (completelykilled).

                                      Table 2                                     __________________________________________________________________________    Herbicidal effects in applica-                                                tion under waterlodged conditions.                                            __________________________________________________________________________                               Herbicidal                                                              Amount of                                                                           effects on                                                              active                                                                              Barn-                                                                             Broad-                                                                            Phyto-                                     Name of              ingredient                                                                          yard                                                                              leaved                                                                            toxicity                                   compound             (g./are)                                                                            grass                                                                             weeds                                                                             on rice                                    __________________________________________________________________________    (1)                  50    5   5   0                                                               25    5   5   0                                                               12.5  4   5   0                                          (2)                  50    5   5   0                                                               25    5   5   0                                                               12.5  5   5   0                                          (iso)C.sub.3 H.sub.7 NHS                                                                           50    4   2   1                                          ∠P∠      25    2   0   0                                          CH.sub.3 OO          12.5  0   0   0                                          U.S. Pat. No. 3,074,790                                                       __________________________________________________________________________

Test Example 3

Pre-emergence application:

Seeds of redroot pigweed, common purslane, common lambsquarter, starwortsp., mouseear chickweed, annual fleabane, chick weed, bitter cress sp.were individually sowed in flower pots. After covering the seeds withsoil, test compounds in such amounts as shown in Table 3 wereindividually applied to the soil. Thereafter, the test plants were grownin a greenhouse and after 20 days from the application, the herbicidaleffects of the individual compounds were investigated to obtain theresults as set forth in Table 3. Herbicidal effects were evaluated bythe numerals ranging from 0 (not damaged) to 5 (completely killed). Allthe compounds were formulated into emulsifiable concentrates, andaqueous dilutions thereof were used.

The results are as follows.

                                      Table 3                                     __________________________________________________________________________              Herbicidal effects on                                               Name                                                                              Amount of                                                                           Red-              Mouse-                                            of  active                                                                              root                                                                              Common                                                                             Common                                                                             Star-                                                                             ear  Annual  Bitter   Pale                                                                              Carpet                                                                             Speed-             com-                                                                              ingredient                                                                          pig-                                                                              purs-                                                                              lambs-                                                                             wort                                                                              chick-                                                                             flea-                                                                             Chick                                                                             cress                                                                              Red smart                                                                             weed well               pound                                                                             (g./are)                                                                            weed                                                                              lane quarter                                                                            sp. weed bane                                                                              weed                                                                              sp.  straw                                                                             weed                                                                              sp.  sp.                __________________________________________________________________________    (1) 10    5   5    4    5   5    5   5   4    4   4   5    4                      5     4   4    4    4   4    4   4   4    4   3   3    4                  (2) 10    5   5    5    5   5    5   5   5    5   5   5    5                      5     4   4    5    4   5    4   5   4    4   4   4    4                  (A) 10    2   1    2    1   1    0   1   1    1   1   1    1                      5     1   0    1    0   0    0   1   0    0   0   0    0                  __________________________________________________________________________    (A) =                                                                              C.sub.2 H.sub.5 OS                                                            ∠P∠      The strongest compound in                                i-C.sub.3 H.sub.7 NHO                                                                              U.S. Pat. No. 3,636,143.                        

Certain organophosphorous compounds tend to destroy or remove myelenfrom nervus system and have delayed neurotoxicity toward human beingthereby causing polyneuritis and especially paralysis at legs. TOCP (triortho cresyl phosphate) is a typical example of such compounds, which issaid to cause Jamaica ginger paralysis. This impediment can beexperimentally reproduced with a highest sensitivity in hens.

The present inventors have examined the toxicities of the presentcompounds and the closely related reference compounds. The results areas follows.

Test Example 4

Hens (age 1 - 1.5 years) were used as test animals. For each testcompound, a suspension was made with a 10 % Tween 80 solution, andorally administered to hend in an amount of 1.0 ml./kg. body. Five weeksafter the administration the toxic symptoms and death were observed. Theleg paralysis was determined by the ataxia. When the acute toxicsymptoms are extreme the observation was made while treating byadministering 10 mg./kg. of atropine sulfate and 50 mg./kg. of PAM(pyridine-2-aldoxime methiodide). The results are shown in Table 1.

                                      Table 4                                     __________________________________________________________________________                                          Number of                                                                     hens with                                                    Admini-                                                                             Number     leg para-                                                                           Occurrence                                             stered                                                                              of         lysis of leg                                                 dosage                                                                              tested                                                                             Dead in                                                                             after paralysis                         Compound             (mg./kg.)                                                                           hens 48 hrs.                                                                             2 weeks                                                                             (%)                               __________________________________________________________________________    (sec)BuNHS           250   1    0     0     0                                 ∠P∠      500   1    0     0     0                                 EtOO                 *750  7    0     0     0                                 (sec)BuNHS           250   5    0     0     0                                 ∠P∠      *500  7    1     0     0                                 MeOO                                                                          (iso)PrNHS           250   7    0     4     57                                ∠P∠      500   7    0     7     100                               C.sub.2 H.sub.5 OO                                                            U.S. Pat. No. 3,636,143                                                       (iso)PrNHS           500   1    0     0     0                                 ∠P∠      1000  5    1     4     100                               CH.sub.3 OO                                                                   U.S. Pat. No. 3,074,790                                                       __________________________________________________________________________     *treated by administering atropine sulfate and PAM                       

As shown in Tables 1, 2 and 3, the herbicidal activities of the presentcompounds are superior to those of reference compounds. Especially, tobroad-leaved weeds the present compounds have higher activity than thereference compound (A) described in U.S. Pat. 3,636,143 which closelyrelates to the present compounds.

Further as shown in Table 4, the reference compounds showedneurotoxicity towards hens, but on the contrary the present compound didnot show any neurotoxicity at all.

It seems that those good characteristics are due to particularsubstituents of 3-methyl, 6-nitro on the benzene ring and N-secondarybutyl.

What we claim is:
 1. A method for controlling weeds, which comprisesapplying an effective amount of a compound of the formula: ##EQU5##
 2. Amethod for controlling weeds, which comprises applying an effective 4.The method of claim 2 wherein the weeds are broad-leaved weeds.